package com.jdbc.utils;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

public class JdbcUtils {
    private static String driver = null;
    private static String url = null;
    private static String username = null;
    private static String password = null;
    static{
        try{
            InputStream in = JdbcUtils.class.getClassLoader().getResourceAsStream("db.properties");
            Properties properties = new Properties();
                properties.load(in);
                driver = properties.getProperty("driver");
                url = properties.getProperty("url");
                username = properties.getProperty("username");
                password = properties.getProperty("password");
                //1.驱动只用加载一次
                Class.forName(driver);
            } catch (IOException | ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
        //获取连接
        public static Connection getConnection() throws SQLException {
            return DriverManager.getConnection(url,username,password);
        }
        //释放连接资源
        public static void release(Connection conn, Statement st, ResultSet rs) {
            if(rs!=null){
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if(st!=null){
                try {
                    st.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if(conn!=null){
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
    }

